Battle of the Brains
by immured-darkness
Summary: [Dexter's Lab and Jimmy Neutron crossover] Dexter's latest invention is nowhere near finished when it propels him into Retroville. However, those he's left behind aren't content to let him disappear into thin air. Chapter Two up.
1. Chapter 1

Author's Note: Posted on this penname so people can't incorrectly state that I don't write. I do, primarily on two other pennames which I surmise no one has figured out.

Given the nature of this story, I doubt it'll receive any attention and therefore, shall linger here while the people who believe I have wronged them take cracks at it without reading first.

Dexter's Laboratory belongs to Gennedy Tartovsky and Jimmy Neutron belongs to John A. Davis and Nick. And really, doesn't a Jimmy Neutron and Dexter's Lab crossover make more sense than a Jimmy Timmy Power Hour? Honestly.

Chapter One: Foolish Endeavours

Working in his lab, Dexter wiped a bead of sweat from his forehead and sighed, leaning against his latest contraption. It had taken him seven hours thus far and it wasn't anywhere near complete. While he relished the physical activity in addition to formulating the equations and drawing up blueprints, he knew that it, like everything else he invented, stood a fair chance of being destroyed by DeeDee. All the hours of work, a labor of love, would be for naught. His meddlesome sister; curse her!

The boy genius grimaced, surveying the devices she'd wrecked yesterday. He hadn't time to mend them and continue the other arduous tasks demanding his attention. Loathe though he was to admit it, he needed an assistant, but the memories of his last few ones weren't conducive to locating one. He also knew that if he attempted to locate one, Mandark would shut him and his lab down immediately, particularly if he knew the reason behind it involved DeeDee.

Overhead, his computer inquired gently and Dexter waved her off. He ought to develop her into a more powerful machine, capable of driving all intruders out, but whenever he had an idea for an invention; he forgot whatever else he was working on and delved into his work. While that meant his huge lab was filled with such creative output, it also meant that each and every device had the propensity to be destroyed.

The logical answer was to create a device capable of funneling his mind into a very narrow scope so he could eliminate the source of his problems, but like everything else, that had a drawback too. If he funneled his mind into such a diminutive area, the chances were he'd somehow blind himself to another important task. Everything he did somehow backfired on him, so if he desired to work on something, he had better think long and hard before he endeavored on it. The lack of foresight killed him every time.

"Deeeex-teeeer," an annoyingly high pitched voice chirped in his ear and he whirled, gloved hands clutching his latest device. DeeDee beamed stupidly at him and he grimaced, aware that there were many, many buttons for her to push and a multitude of things that could go "boom" and with them, send him skyrocketing into the ceiling. Dexter pancake. Not pretty.

"What _is_ it?" Dexter retorted, eyes flashing. "Can't you see you're impeding _science_?"

"Oooh..." DeeDee said, grinning from ear to ear and eyes widened at the object in his hand. "What's_ that_?"

"This?" Dexter attempted to conceal his creation, but it was too late. DeeDee had already spotted it and snatched it out of his hand before he could as much as protest. The horrible thing was if he "tattled" on her, his parents would insist he had to share. Him, share his inventions with his idiot sister? Not a chance.

The small metallic device bounced in her large hands and each time it did, Dexter's stomach lurched. This particular machine could create small wormholes and, in addition to enabling interdimensional travel, bring people out of their native worlds and into this one. Unlike his other interdimensional portal, this one filtered potentially dangerous creatures and prevented their entrance. Dexter had high hopes for it, but if DeeDee demolished it, he'd be thwarted before he even attempted it.

"Don't you have something better to do?" Dexter asked pointedly, jumping up to retrieve it but failing miserably thanks to their height difference. DeeDee hummed, dancing around nonchalantly and driving his temper higher. She tossed it from hand to hand like a juggler might and it nearly plummeted to the ground. In that instant, Dexter saw its life flashing before his eyes. The initial conception, scribbling madly to figure out just how it would work, drawing up the blueprints, ascertaining which materials would best serve him, tinkering with it...and then, like everything else, its eventual demise at DeeDee's hands.

"_Maybe_," DeeDee replied, bouncing gleefully and spinning around, her long legs threatening to demolish still more of his lab. Desperate, Dexter commanded the computer to avert her calamitous path, but the steel arms failed to reach their target. She played in his lab like it was a game. Like destroying his hard wrought inventions was a _game_. Dexter growled at the thought.

He had to escape her, if only momentarily. While the machine in her hands was far from complete, it might function well enough to provide a decent exit. Hopefully, whatever universe he landed in had the technology necessary to transport him home and maybe, just maybe, he'd locate a fellow scientist with whom to share his most brilliant ideas. There was never anyone here with whom he could speak other than Mandark and the two loathed each other.

"Oooh," DeeDee cried, dancing and whirling into a corner of his lab where his wires and power supply ran. In a dingy, dusty area dwelt the computer's off switch, which, if pushed, would shut it off and send the lab into chaos. Dexter really had to stop designing his lab like that. His lack of foresight was giving DeeDee easy maneuverability.

"What does _that_ do?" she trilled and her finger hovered precariously over it. Tossing his device away like it was meaningless, she fingered the switch. Dexter lunged, barely catching his beloved creation and he cradled it to his chest. Unfortunately, he didn't have long to relish its safe return because about five seconds later, the lab was sent into a melt down thanks to DeeDee. Warning whistles, sirens, and booms filled the air and DeeDee, predictably, waltzed off into areas unknown.

"I have had it!" Dexter pronounced, slamming his device down by accident. "No more DeeDees, no more intrusions, no more unwanted guests in my laboratory! I have-"

A cloud of pink smoke enveloped him and the last thing he said before leaving this universe was a soft, "Uh-oh."

* * *

Jimmy Neutron, meanwhile, studied his latest invention at all angles and grinned at Goddard, who woofed enthusiastically back. This particular device would filter certain _people_ whose name rhymed with "Immy Urner" from entering Retroville uninvited. After the last few "adventures", he'd rather dangle above hungry piranhas than deal with him again. In fact, he could think of a plethora of things he'd rather contend with than Timmy. Goddard had already drawn up an impressive list.

"A few more modifications and it ought to be complete," Jimmy said, wiping his brow. In a few hours, he had a date with Carl, Sheen, Libby, and Cindy at the Candy Bar and he preferred to complete as much as he could of the interdimensional modifier as possible. Unfortunately, pioneering it meant journeying into Dimmsdale to acquire a bit of Timmy's DNA to prevent him from dropping in. Jimmy shuddered at the thought of their last encounter. He must have been under the influence of heavy narcotics in the first place to consider befriending him.

Yanking a Purple Flurp out of the fridge, he popped the can open and sipped happily. He strolled over to his lab chair to enjoy a brief but well deserved rest while Goddard checked the preliminary functions of the device. It wouldn't do to affix it to the portal and then have the entire thing explode in a violent (but entertaining) fireworks display. He'd been much more careful lately with his inventions, since he knew that the slightest incorrect calculation or maladjustment could demolish everything. Also, Cindy had commenced to pick on him about it and reminded him of his various well intentioned but less than stellar in execution "Jim-tech".

Goddard's mini helicopter blades spun atop his head and he prodded the interdimensional portal with his snout. Jimmy grimaced, recalling Timmy slipping his insipid video game inside him and wreaking havoc with his beloved dog's programming. Well, with the completion of his new ancillary piece, he'd never have to worry about him or anyone else cropping up. No more ludicrous prestidigitation, trite yet realistic holograms and, above all, no more unwanted visitors. At the thought, Jimmy grinned and Goddard barked, affirming his master's cheeriness.

And Cindy, although she wasn't at the moment, would be all his.

* * *

"Well, this was unanticipated," Dexter remarked to himself and, in the void in which he found himself currently, his voice echoed. He could distinguish nothing and wherever he walked, the darkness consumed his path. He didn't dare retreat and thus, plodded miserably onward. A genius though he might be, he was only eight and more than a little afraid of the dark. It didn't help that no matter where he turned, there was nothing but it everywhere. And in his lab or his room, he never had to subsist in a pitch black locale. 

Judging by the area surrounding him, beneath his panic, he deemed that he was in the space between dimensions. While titling it pacified him slightly, Dexter never thought terribly well under duress and now was no exception. For once, he would have given anything to have DeeDee beside him babbling incoherently. At least it'd eliminate the stark nothingness.

"Just because it is dark means nothing," he told himself. "After all, darkness is an essential component in many scientific things. Black holes, outer space...monstrous beings from other dimensions..."

Gulping, he spurted forward. Where was the proverbial light that people always went on about? Why on earth was it so confoundedly dark? Dexter's heart skipped a beat and he refrained from screaming, but it was exceedingly difficult. He was petrified.

Knees buckling, he mentally commanded himself to calm. While that might have worked with an older child, it did absolutely nothing to help in this instance. He heard, distantly, DeeDee crashing around his lab and Mandark arriving on the scene. He wanted to run in that direction, but he didn't know where it was anymore or his exact location. He couldn't tell which end was up.

"DeeDee?" Dexter cried. "Mandark? Computer? Anyone?"

No one. The infernal dark loomed and Dexter whimpered. Stubbornly stepping ahead, he hoped fervently he'd unearth some light sooner or later. Perhaps if he focused his energies on arriving at a destination, any destination, he'd depart from this hellish realm.

Shutting his eyes (since it made no difference where he opened them or not here), he concentrated hard on a lab. A lab included scientists, none of whom would scorn his infantile terror, he hoped. Especially since he planned to keep that his little secret. A lab also included technology with which he could use to return to his universe.

Barely audible, he heard a boom and shuddered. Perhaps he ought to postpone his return. He'd rather not bear witness to his lab's destruction.

"A lab...any lab at all...I'm not choosy...c'mon..."

A light enveloped him and Dexter found himself dumped unceremoniously onto a hard surface. Without preamble, too grateful to care that it was contrary to his nature, Dexter latched himself onto the first person he saw. He blathered on incoherently and a hand pushed him off.

"Goddard, I thought that the contraption was supposed to filter out unwelcome visitors," the boy said and Dexter glanced up, having his first look at Jimmy Neutron, boy genius.


	2. Chapter 2

Author's Note: Allow me to lapse into "Jumba speech" and say "please be to note that I have disabled anonymous reviewing, so if you are desiring to review in this fashion, you cannot. Hee, hee!"

There's a few reasons for this. One, if you're that cowardly that you deign to hide behind an anonymous review, you'll be unable to do so (and I have recently removed an anonymous review which I believe served this purpose). Two, since anonymous reviewing is now disabled, I can reply to whatever little comment your smart mouth provides. Snarky, yes?

I know I've only got one review thus far (since I deleted the other one) and I'll receive reprimands for acting like I'm some sort of "big-shot writer", but I don't really care. I'm not really immured-darkness, I'm actually someone fairly well known on this site (at least, in the JN section), and I could really give a crap who wants to take a shot at me on this account.

Oh, and Dexter's and Jimmy Neutron aren't mine.

Chapter Two

Jimmy Neutron regarded the smaller boy with a mixture of disgust and curiosity. Unfortunately, given his recent experiences with Timmy Turner and his friends, he wouldn't put it past the pink hatted loser to locate another of his two dimensional friends and transport him instead. Timmy loved ruining his life, didn't he? This one probably would immediately affix himself to Cindy, too, and thereby destroy the precarious relationship they'd built. Okay, so it wasn't much of one, but Jimmy really didn't appreciate interlopers. It was getting very tired and pedantic.

"A lab!" the boy exclaimed, with an Austrian accent. He dusted himself off and Jimmy noticed he wore a lab coat and purple gloves. Glancing down, he realized he too was wearing his lab coat, but it was dirty thanks to the grease he'd utilized previously. So it was another one of Timmy's smart friends. Big deal. He didn't care. He'd dispose of him as easily as he had the others.

"A real lab!" the boy continued, trilling over his inventions. "But it's rather small and confined. How can you accomplish anything in a grotto?"

"I beg your pardon!" Jimmy snapped, whirling the kid around and glaring at him. Behind large glasses, bright and inquisitive green eyes peered at his sapphire ones. The red haired boy grinned sheepishly and Goddard barked warningly, tail wagging.

"Goddard," Jimmy called, "configure the portal to release Turner's friend back into Dimmsdale."

"Dimmsdale?" the boy repeated, frowning. "But I do not live in Dimmsdale. I have not even heard of it. And who is this Turner?"

Jimmy glared at him and the boy turned away, glancing eagerly at his shrink ray. Memories of reducing Retroville's denizens to six inch forms flashed through his mind and he grimaced, wrenching it out of his hands. Nonetheless, he soon located another device, his cloning apparatus, and studied it appreciatively. Jimmy's fists balled. This boy obviously meant to usurp his genius and capitalize on it.

"Quit this farce!" Jimmy retorted and the boy shrugged.

"I do not know what you are talking about," he replied. "I am Dexter and you..."

A grin split Dexter's face and he beamed, taking in all the wonderful things Jimmy had created. He looked like a kid in a candy shop; his jade eyes were alight even when they spotted Goddard.

* * *

Dexter bounced gleefully, more like his older sister than he'd ever admit at the moment. He scanned this "Goddard" from every angle and Goddard barked fiercely, snapping his jaws at Dexter's face. Nonetheless, despite fear gnawing at him, the auburn haired boy was too excited to be frightened. Another boy who designed robots, apparently, and if this lab was anything to go by, then they had to be kindred spirits. Oh, he'd quested forever to locate a person like him who didn't demand he shut down his lab or demean him at every turn. A friend, perhaps?

"You're a genius like me!" Dexter cried, leaping forth and shaking Jimmy's hand. The brown haired boy looked anything but accommodating, however. In fact, he appeared downright antagonized.

"Dexter or whoever you are," Jimmy snapped, eyes flashing, "GET OUT OF MY LABORATORY!"

Dexter halted. Wow, that particular phrase sounded rather familiar. Now, where had he heard it before? Hmm. Different voice, but he could have sworn he'd heard that uttered before. Oh, yeah. He said it to DeeDee countless times. But wait, Jimmy couldn't be shoving him out of his lab. He needed to get home, first off, and while he could postpone that (and witnessing the wreckage DeeDee and Mandark caused), his scientific curiosity was aroused. He'd love to figure out how Jimmy's devices worked compared to his and basically everything about him.

A female voice alerted Jimmy to newcomers standing by the entrance to a clubhouse. One particular girl, a blonde haired girl who copped an attitude problem, reminded Dexter of DeeDee and he shuddered. Jimmy glanced at Dexter and scowled before activating a microphone that carried his voice out to them.

"Guys, I'm experiencing a small _inconvenience_," Jimmy snapped and the blonde girl huffed.

"Whatever, Neutron," she snapped. "Either you're joining us to the Candy Bar or I'm hauling your sorry butt out and dragging you up there myself."

"You cannot let your sister into your lab! It is sacred!" Dexter cried, shoving Jimmy away from the mike and inadvertently speaking into it. "She will destroy everything! I should know, my older sister cannot leave mine alone!"

Jimmy and the girl both promptly choked and, behind them, the Mexican boy burst into laughter. The rotund boy looked confused and the African American girl simply shook her head and tutted disapprovingly. Meanwhile, Jimmy stared blankly at Dexter like he'd never seen him before. This, come to think of it, was pretty close to the truth.

"Why does your sister call you by your last name?" Dexter inquired innocently. Outside, the Mexican boy was laughing his bloody head off and the larger boy had joined in, despite the blonde haired girl's mutinous gaze.

"So _that's_ why you two haven't hooked up yet," the Mexican boy said. "You're related!"

At which point, the large boy looked like he was going to die laughing and the African American girl slapped the Mexican boy in the back of the head. The blonde girl sputtered and, to Dexter's surprise, Jimmy started laughing too. In fact, he nearly fell over because he was guffawing so hard.

"I do not understand," Dexter said blankly. "What is so amusing?"

Jimmy took one look at Dexter and laughed harder. Clutching his stomach mirthfully, he eventually calmed himself down and then shivered as the blonde haired girl slammed her fist into the clubhouse's wooden planks outside. If looks could kill, her profession would be staring because she looked murderous.

"Neutron, I am _not_ your sister and this isn't funny!" she screamed and Dexter, completely befuddled, gawked. Jimmy straightened himself up and wiped a tear from his eye.

"Dexter," Jimmy said, still smiling, "that's Cindy. She's my...that's Cindy."

Cindy scoffed, kicking the door contemptuously. Her emerald eyes flashed dangerously and Dexter gulped, once again glancing at Jimmy. Nonetheless, despite Cindy's malevolence, Jimmy seemed collected and thus, Dexter hoped he would be fine. Cindy reminded him of DeeDee except with a larger attitude and shorter legs. And, you know, minus the ballerina outfit.

"She's that annoying girl that always follows Jimmy around and acts like she doesn't like him," the Mexican boy continued and both Cindy and Jimmy blushed.

"Yeah, and we all know she does, so she should quit while she's ahead," the larger boy said and Cindy's response was a swift but brutal karate chop to the stomach. He doubled over, clutching his midsection, and Cindy smirked. Dexter gulped again, ill at ease despite Jimmy's nonchalance. Couldn't he see this girl was dangerous?

The African American girl rolled her eyes and inquired politely, "New visitors from another dimension, Jimmy?"

Jimmy groaned, rubbing the back of his neck. Glancing at Dexter once more, he pressed a button and both boys were ejected outside. Dexter blinked, realizing that Jimmy's lab was not exactly in the most secretive place unlike his. And these people, why were they here? Why would he let them know his precious secret? What was wrong with him?

"Why do all these people know you have a lab?" Dexter cried, aghast. "Especially that girl that you say is not your sister but she must be because she has that high, grating voice and a disregard for your technology."

Cindy whirled on him and Dexter laughed nervously. Ducking behind the trash can in front of the clubhouse, he cowered and Jimmy quickly yanked her away before she harmed him like she had the other boy. He'd never met a more terrifying girl in his life, Mandark's sister notwithstanding. And it didn't help that Jimmy and Cindy were now having an argument about him since Cindy desired to "kick his butt" for his "smart mouth".

"At least he's not in love with you," the African American girl remarked, shaking her head. "I think you've had enough boy troubles, girl."

"I do _not_ have a high and grating voice!" Cindy snapped, glaring at the other two boys, who whistled innocently. She rounded on them too and Jimmy had to grab her by the waist to keep her from pummeling them. Dexter, behind the trash can, swallowed hard. This was truly a terrifying dimension.

"I like this kid!" the Mexican boy proclaimed and held out a hand to Dexter. Dexter regarded it dubiously and, before he could protest, he'd yanked him out into the open. Cindy growled warningly and Dexter's knees buckled.

"I'm Sheen and this is Carl," Sheen said, pointing out himself and the other boy in turn. "And that hot girl over there is my girlfriend, Libby."

"You _wish_," Libby muttered under her breath. "But yeah, I'm Libby."

Utterly focused on annihilating Dexter, Cindy snarled and fought Jimmy, although he noticed that whenever Jimmy's hands accidentally brushed hers or she drew too close to him, she'd suddenly stop. Both parties were exceedingly uncomfortable with the arrangements and Dexter reluctantly (and fretfully apologized). While that didn't exactly soothe Cindy to the point of removing her homicidal rage, it reduced her temper a bit.

"Are you sure you're not his sister?" Dexter asked once the danger had passed.

"I'm _positive_," Cindy spat. "Neutron is my _rival_."

"Then why do you let her know where your lab is? What is _wrong_ with you?" Dexter cried. "She will destroy it! Are you insane!"

"Destroy it?" Cindy repeated blankly. "Why would I destroy Neutron's lab?"

"Because only one genius can have a lab!" Dexter explained like she was an idiot. "If Jimmy has one, then it threatens Cindy's."

"Um..." Sheen said, staring. Dexter didn't understand why everyone was so confused. Mandark would have dearly loved for an opportunity to demolish his lab and the way Jimmy prostrated his, it'd only be a matter of time before Cindy destroyed it. She was, after all, his rival. Moreover, if she was blonde like DeeDee, she'd probably dance around it and push buttons until everything broke or exploded. Why didn't they get it?

"We'd better take him to the Candy Bar and straighten him out," Libby said, draping an arm around Dexter's shoulders.

"Yeah..." Cindy said, befuddled. Jimmy shook his head, hung up on the idea of Cindy being related to him.

"Lead on," Jimmy said, frowning.

* * *


End file.
